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 // Copyright Ruslan Arutyunyan, 2019-2021.
 // Copyright Antony Polukhin, 2021-2023.
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
 // Contributed by Ruslan Arutyunyan
 
 #ifndef BOOST_ANYS_BASIC_ANY_HPP_INCLUDED
 #define BOOST_ANYS_BASIC_ANY_HPP_INCLUDED
 
 #include <boost/config.hpp>
 #ifdef BOOST_HAS_PRAGMA_ONCE
 # pragma once
 #endif
 
 /// \file boost/any/basic_any.hpp
 /// \brief \copybrief boost::anys::basic_any
 
 #include <boost/any/bad_any_cast.hpp>
 #include <boost/any/fwd.hpp>
 #include <boost/assert.hpp>
 #include <boost/type_index.hpp>
 #include <boost/throw_exception.hpp>
 
 #include <memory>  // for std::addressof
 #include <type_traits>
 
 
 namespace boost {
 
 namespace anys {
 
     /// \brief A class with customizable Small Object Optimization whose
     /// instances can hold instances of any type that satisfies
     /// \forcedlink{ValueType} requirements. Use boost::any instead if not sure.
     ///
     /// boost::anys::basic_any is the drop-in replacement for boost::any
     /// that provides control over Small Object Optimization via
     /// `OptimizeForSize` and `OptimizeForAlignment` template parameters.
     ///
     /// There are certain applications that require boost::any
     /// functionality, do know the typical/maximal size of the stored object and
     /// wish to avoid dynamic memory allocation overhead. For the convenience
     /// such applications may create a typedef for boost::anys::basic_any
     /// with the `OptimizeForSize` and `OptimizeForAlignment` template
     /// parameters set to typical/maximal size and alignment of types
     /// respectively. Memory allocation would be avoided for storing nothrow
     /// move constructible types with size and alignment less than or
     /// equal to the `OptimizeForSize` and `OptimizeForAlignment` values.
     ///
     /// Otherwise just use boost::any.
     template <std::size_t OptimizeForSize, std::size_t OptimizeForAlignment>
     class basic_any
     {
         static_assert(OptimizeForSize > 0 && OptimizeForAlignment > 0, "Size and Align shall be positive values");
         static_assert(OptimizeForSize >= OptimizeForAlignment, "Size shall non less than Align");
         static_assert((OptimizeForAlignment & (OptimizeForAlignment - 1)) == 0, "Align shall be a power of 2");
         static_assert(OptimizeForSize % OptimizeForAlignment == 0, "Size shall be multiple of alignment");
     private:
         /// @cond
         enum operation
         {
             Destroy,
             Move,
             Copy,
             AnyCast,
             UnsafeCast,
             Typeinfo
         };
 
         template <typename ValueType>
         static void* small_manager(operation op, basic_any& left, const basic_any* right, const boost::typeindex::type_info* info)
         {
             switch (op)
             {
                 case Destroy:
                     BOOST_ASSERT(!left.empty());
                     reinterpret_cast<ValueType*>(&left.content.small_value)->~ValueType();
                     break;
                 case Move: {
                     BOOST_ASSERT(left.empty());
                     BOOST_ASSERT(right);
                     BOOST_ASSERT(!right->empty());
                     BOOST_ASSERT(right->type() == boost::typeindex::type_id<ValueType>());
                     ValueType* value = reinterpret_cast<ValueType*>(&const_cast<basic_any*>(right)->content.small_value);
                     new (&left.content.small_value) ValueType(std::move(*value));
                     left.man = right->man;
                     reinterpret_cast<ValueType const*>(&right->content.small_value)->~ValueType();
                     const_cast<basic_any*>(right)->man = 0;
 
                     };
                     break;
 
                 case Copy:
                     BOOST_ASSERT(left.empty());
                     BOOST_ASSERT(right);
                     BOOST_ASSERT(!right->empty());
                     BOOST_ASSERT(right->type() == boost::typeindex::type_id<ValueType>());
                     new (&left.content.small_value) ValueType(*reinterpret_cast<const ValueType*>(&right->content.small_value));
                     left.man = right->man;
                     break;
                 case AnyCast:
                     BOOST_ASSERT(info);
                     BOOST_ASSERT(!left.empty());
                     return boost::typeindex::type_id<ValueType>() == *info ?
                             reinterpret_cast<typename std::remove_cv<ValueType>::type *>(&left.content.small_value) : 0;
                 case UnsafeCast:
                     BOOST_ASSERT(!left.empty());
                     return reinterpret_cast<typename std::remove_cv<ValueType>::type *>(&left.content.small_value);
                 case Typeinfo:
                     return const_cast<void*>(static_cast<const void*>(&boost::typeindex::type_id<ValueType>().type_info()));
             }
 
             return 0;
         }
 
         template <typename ValueType>
         static void* large_manager(operation op, basic_any& left, const basic_any* right, const boost::typeindex::type_info* info)
         {
             switch (op)
             {
                 case Destroy:
                     BOOST_ASSERT(!left.empty());
                     delete static_cast<ValueType*>(left.content.large_value);
                     break;
                 case Move:
                     BOOST_ASSERT(left.empty());
                     BOOST_ASSERT(right);
                     BOOST_ASSERT(!right->empty());
                     BOOST_ASSERT(right->type() == boost::typeindex::type_id<ValueType>());
                     left.content.large_value = right->content.large_value;
                     left.man = right->man;
                     const_cast<basic_any*>(right)->content.large_value = 0;
                     const_cast<basic_any*>(right)->man = 0;
                     break;
                 case Copy:
                     BOOST_ASSERT(left.empty());
                     BOOST_ASSERT(right);
                     BOOST_ASSERT(!right->empty());
                     BOOST_ASSERT(right->type() == boost::typeindex::type_id<ValueType>());
                     left.content.large_value = new ValueType(*static_cast<const ValueType*>(right->content.large_value));
                     left.man = right->man;
                     break;
                 case AnyCast:
                     BOOST_ASSERT(info);
                     BOOST_ASSERT(!left.empty());
                     return boost::typeindex::type_id<ValueType>() == *info ?
                             static_cast<typename std::remove_cv<ValueType>::type *>(left.content.large_value) : 0;
                 case UnsafeCast:
                     BOOST_ASSERT(!left.empty());
                     return reinterpret_cast<typename std::remove_cv<ValueType>::type *>(left.content.large_value);
                 case Typeinfo:
                     return const_cast<void*>(static_cast<const void*>(&boost::typeindex::type_id<ValueType>().type_info()));
             }
 
             return 0;
         }
 
         template <typename ValueType>
         struct is_small_object : std::integral_constant<bool, sizeof(ValueType) <= OptimizeForSize &&
             alignof(ValueType) <= OptimizeForAlignment &&
             std::is_nothrow_move_constructible<ValueType>::value>
         {};
 
         template <typename ValueType>
         static void create(basic_any& any, const ValueType& value, std::true_type)
         {
             typedef typename std::decay<const ValueType>::type DecayedType;
 
             any.man = &small_manager<DecayedType>;
             new (&any.content.small_value) ValueType(value);
         }
 
         template <typename ValueType>
         static void create(basic_any& any, const ValueType& value, std::false_type)
         {
             typedef typename std::decay<const ValueType>::type DecayedType;
 
             any.man = &large_manager<DecayedType>;
             any.content.large_value = new DecayedType(value);
         }
 
         template <typename ValueType>
         static void create(basic_any& any, ValueType&& value, std::true_type)
         {
             typedef typename std::decay<const ValueType>::type DecayedType;
             any.man = &small_manager<DecayedType>;
             new (&any.content.small_value) DecayedType(std::forward<ValueType>(value));
         }
 
         template <typename ValueType>
         static void create(basic_any& any, ValueType&& value, std::false_type)
         {
             typedef typename std::decay<const ValueType>::type DecayedType;
             any.man = &large_manager<DecayedType>;
             any.content.large_value = new DecayedType(std::forward<ValueType>(value));
         }
         /// @endcond
 
     public: // non-type template parameters accessors
             static constexpr std::size_t buffer_size = OptimizeForSize;
             static constexpr std::size_t buffer_align = OptimizeForAlignment;
 
     public: // structors
 
         /// \post this->empty() is true.
         constexpr basic_any() noexcept
             : man(0), content()
         {
         }
 
         /// Makes a copy of `value`, so
         /// that the initial content of the new instance is equivalent
         /// in both type and value to `value`.
         ///
         /// Does not dynamically allocate if `ValueType` is nothrow
         /// move constructible and `sizeof(value) <= OptimizeForSize` and
         /// `alignof(value) <= OptimizeForAlignment`.
         ///
         /// \throws std::bad_alloc or any exceptions arising from the copy
         /// constructor of the contained type.
         template<typename ValueType>
         basic_any(const ValueType & value)
             : man(0), content()
         {
             static_assert(
                 !std::is_same<ValueType, boost::any>::value,
                 "boost::anys::basic_any shall not be constructed from boost::any"
             );
             static_assert(
                 !anys::detail::is_basic_any<ValueType>::value,
                 "boost::anys::basic_any<A, B> shall not be constructed from boost::anys::basic_any<C, D>"
             );
             create(*this, value, is_small_object<ValueType>());
         }
 
         /// Copy constructor that copies content of
         /// `other` into new instance, so that any content
         /// is equivalent in both type and value to the content of
         /// `other`, or empty if `other` is empty.
         ///
         /// \throws May fail with a `std::bad_alloc`
         /// exception or any exceptions arising from the copy
         /// constructor of the contained type.
         basic_any(const basic_any & other)
           : man(0), content()
         {
             if (other.man)
             {
                 other.man(Copy, *this, &other, 0);
             }
         }
 
         /// Move constructor that moves content of
         /// `other` into new instance and leaves `other` empty.
         ///
         /// \post other->empty() is true
         /// \throws Nothing.
         basic_any(basic_any&& other) noexcept
           : man(0), content()
         {
             if (other.man)
             {
                 other.man(Move, *this, &other, 0);
             }
         }
 
         /// Forwards `value`, so
         /// that the initial content of the new instance is equivalent
         /// in both type and value to `value` before the forward.
         ///
         /// Does not dynamically allocate if `ValueType` is nothrow
         /// move constructible and `sizeof(value) <= OptimizeForSize` and
         /// `alignof(value) <= OptimizeForAlignment`.
         ///
         /// \throws std::bad_alloc or any exceptions arising from the move or
         /// copy constructor of the contained type.
         template<typename ValueType>
         basic_any(ValueType&& value
             , typename std::enable_if<!std::is_same<basic_any&, ValueType>::value >::type* = 0 // disable if value has type `basic_any&`
             , typename std::enable_if<!std::is_const<ValueType>::value >::type* = 0) // disable if value has type `const ValueType&&`
           : man(0), content()
         {
             typedef typename std::decay<ValueType>::type DecayedType;
             static_assert(
                 !std::is_same<DecayedType, boost::any>::value,
                 "boost::anys::basic_any shall not be constructed from boost::any"
             );
             static_assert(
                 !anys::detail::is_basic_any<DecayedType>::value,
                 "boost::anys::basic_any<A, B> shall not be constructed from boost::anys::basic_any<C, D>"
             );
             create(*this, static_cast<ValueType&&>(value), is_small_object<DecayedType>());
         }
 
         /// Releases any and all resources used in management of instance.
         ///
         /// \throws Nothing.
         ~basic_any() noexcept
         {
             if (man)
             {
                 man(Destroy, *this, 0, 0);
             }
         }
 
     public: // modifiers
 
         /// Exchange of the contents of `*this` and `rhs`.
         ///
         /// \returns `*this`
         /// \throws Nothing.
         basic_any & swap(basic_any & rhs) noexcept
         {
             if (this == &rhs)
             {
                 return *this;
             }
 
             if (man && rhs.man)
             {
                 basic_any tmp;
                 rhs.man(Move, tmp, &rhs, 0);
                 man(Move, rhs, this, 0);
                 tmp.man(Move, *this, &tmp, 0);
             }
             else if (man)
             {
                 man(Move, rhs, this, 0);
             }
             else if (rhs.man)
             {
                 rhs.man(Move, *this, &rhs, 0);
             }
             return *this;
         }
 
         /// Copies content of `rhs` into
         /// current instance, discarding previous content, so that the
         /// new content is equivalent in both type and value to the
         /// content of `rhs`, or empty if `rhs.empty()`.
         ///
         /// \throws std::bad_alloc
         /// or any exceptions arising from the copy constructor of the
         /// contained type. Assignment satisfies the strong guarantee
         /// of exception safety.
         basic_any & operator=(const basic_any& rhs)
         {
             basic_any(rhs).swap(*this);
             return *this;
         }
 
         /// Moves content of `rhs` into
         /// current instance, discarding previous content, so that the
         /// new content is equivalent in both type and value to the
         /// content of `rhs` before move, or empty if
         /// `rhs.empty()`.
         ///
         /// \post `rhs->empty()` is true
         /// \throws Nothing.
         basic_any & operator=(basic_any&& rhs) noexcept
         {
             rhs.swap(*this);
             basic_any().swap(rhs);
             return *this;
         }
 
         /// Forwards `rhs`,
         /// discarding previous content, so that the new content of is
         /// equivalent in both type and value to
         /// `rhs` before forward.
         ///
         /// Does not dynamically allocate if `ValueType` is nothrow
         /// move constructible and `sizeof(value) <= OptimizeForSize` and
         /// `alignof(value) <= OptimizeForAlignment`.
         ///
         /// \throws std::bad_alloc
         /// or any exceptions arising from the move or copy constructor of the
         /// contained type. Assignment satisfies the strong guarantee
         /// of exception safety.
         template <class ValueType>
         basic_any & operator=(ValueType&& rhs)
         {
             typedef typename std::decay<ValueType>::type DecayedType;
             static_assert(
                 !std::is_same<DecayedType, boost::any>::value,
                 "boost::any shall not be assigned into boost::anys::basic_any"
             );
             static_assert(
                 !anys::detail::is_basic_any<DecayedType>::value || std::is_same<DecayedType, basic_any>::value,
                 "boost::anys::basic_any<A, B> shall not be assigned into boost::anys::basic_any<C, D>"
             );
             basic_any(std::forward<ValueType>(rhs)).swap(*this);
             return *this;
         }
 
     public: // queries
 
         /// \returns `true` if instance is empty, otherwise `false`.
         /// \throws Nothing.
         bool empty() const noexcept
         {
             return !man;
         }
 
         /// \post this->empty() is true
         void clear() noexcept
         {
             basic_any().swap(*this);
         }
 
         /// \returns the `typeid` of the
         /// contained value if instance is non-empty, otherwise
         /// `typeid(void)`.
         ///
         /// Useful for querying against types known either at compile time or
         /// only at runtime.
         const boost::typeindex::type_info& type() const BOOST_NOEXCEPT
         {
             return man
                     ? *static_cast<const boost::typeindex::type_info*>(man(Typeinfo, const_cast<basic_any&>(*this), 0, 0))
                     : boost::typeindex::type_id<void>().type_info();
         }
 
     private: // representation
         /// @cond
         template<typename ValueType, std::size_t Size, std::size_t Alignment>
         friend ValueType * any_cast(basic_any<Size, Alignment> *) noexcept;
 
         template<typename ValueType, std::size_t Size, std::size_t Alignment>
         friend ValueType * unsafe_any_cast(basic_any<Size, Alignment> *) noexcept;
 
         typedef void*(*manager)(operation op, basic_any& left, const basic_any* right, const boost::typeindex::type_info* info);
 
         manager man;
 
         union content {
             void * large_value;
             alignas(OptimizeForAlignment) unsigned char small_value[OptimizeForSize];
         } content;
         /// @endcond
     };
 
     /// Exchange of the contents of `lhs` and `rhs`.
     /// \throws Nothing.
     template<std::size_t OptimizeForSize, std::size_t OptimizeForAlignment>
     void swap(basic_any<OptimizeForSize, OptimizeForAlignment>& lhs, basic_any<OptimizeForSize, OptimizeForAlignment>& rhs) noexcept
     {
         lhs.swap(rhs);
     }
 
     /// \returns Pointer to a ValueType stored in `operand`, nullptr if
     /// `operand` does not contain specified `ValueType`.
     template<typename ValueType, std::size_t Size, std::size_t Alignment>
     ValueType * any_cast(basic_any<Size, Alignment> * operand) noexcept
     {
         return operand->man ?
                 static_cast<typename std::remove_cv<ValueType>::type *>(operand->man(basic_any<Size, Alignment>::AnyCast, *operand, 0, &boost::typeindex::type_id<ValueType>().type_info()))
                 : 0;
     }
 
     /// \returns Const pointer to a ValueType stored in `operand`, nullptr if
     /// `operand` does not contain specified `ValueType`.
     template<typename ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment>
     inline const ValueType * any_cast(const basic_any<OptimizeForSize, OptimizeForAlignment> * operand) noexcept
     {
         return boost::anys::any_cast<ValueType>(const_cast<basic_any<OptimizeForSize, OptimizeForAlignment> *>(operand));
     }
 
     /// \returns ValueType stored in `operand`
     /// \throws boost::bad_any_cast if `operand` does not contain
     /// specified ValueType.
     template<typename ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment>
     ValueType any_cast(basic_any<OptimizeForSize, OptimizeForAlignment> & operand)
     {
         typedef typename std::remove_reference<ValueType>::type nonref;
 
         nonref * result = boost::anys::any_cast<nonref>(std::addressof(operand));
         if(!result)
             boost::throw_exception(bad_any_cast());
 
         // Attempt to avoid construction of a temporary object in cases when
         // `ValueType` is not a reference. Example:
         // `static_cast<std::string>(*result);`
         // which is equal to `std::string(*result);`
         typedef typename std::conditional<
             std::is_reference<ValueType>::value,
             ValueType,
             typename std::add_lvalue_reference<ValueType>::type
         >::type ref_type;
 
 #ifdef BOOST_MSVC
 #   pragma warning(push)
 #   pragma warning(disable: 4172) // "returning address of local variable or temporary" but *result is not local!
 #endif
         return static_cast<ref_type>(*result);
 #ifdef BOOST_MSVC
 #   pragma warning(pop)
 #endif
     }
 
     /// \returns `ValueType` stored in `operand`
     /// \throws boost::bad_any_cast if `operand` does not contain
     /// specified `ValueType`.
     template<typename ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment>
     inline ValueType any_cast(const basic_any<OptimizeForSize, OptimizeForAlignment> & operand)
     {
         typedef typename std::remove_reference<ValueType>::type nonref;
         return boost::anys::any_cast<const nonref &>(const_cast<basic_any<OptimizeForSize, OptimizeForAlignment> &>(operand));
     }
 
     /// \returns `ValueType` stored in `operand`, leaving the `operand` empty.
     /// \throws boost::bad_any_cast if `operand` does not contain
     /// specified `ValueType`.
     template<typename ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment>
     inline ValueType any_cast(basic_any<OptimizeForSize, OptimizeForAlignment>&& operand)
     {
         static_assert(
             std::is_rvalue_reference<ValueType&&>::value /*true if ValueType is rvalue or just a value*/
             || std::is_const< typename std::remove_reference<ValueType>::type >::value,
             "boost::any_cast shall not be used for getting nonconst references to temporary objects"
         );
         return boost::anys::any_cast<ValueType>(operand);
     }
 
 
     /// @cond
 
     // Note: The "unsafe" versions of any_cast are not part of the
     // public interface and may be removed at any time. They are
     // required where we know what type is stored in the any and can't
     // use typeid() comparison, e.g., when our types may travel across
     // different shared libraries.
     template<typename ValueType, std::size_t OptimizedForSize, std::size_t OptimizeForAlignment>
     inline ValueType * unsafe_any_cast(basic_any<OptimizedForSize, OptimizeForAlignment> * operand) noexcept
     {
         return static_cast<ValueType*>(operand->man(basic_any<OptimizedForSize, OptimizeForAlignment>::UnsafeCast, *operand, 0, 0));
     }
 
     template<typename ValueType, std::size_t OptimizeForSize, std::size_t OptimizeForAlignment>
     inline const ValueType * unsafe_any_cast(const basic_any<OptimizeForSize, OptimizeForAlignment> * operand) noexcept
     {
         return boost::anys::unsafe_any_cast<ValueType>(const_cast<basic_any<OptimizeForSize, OptimizeForAlignment> *>(operand));
     }
     /// @endcond
 
 } // namespace anys
 
 using boost::anys::any_cast;
 using boost::anys::unsafe_any_cast;
 
 } // namespace boost
 
 #endif // #ifndef BOOST_ANYS_BASIC_ANY_HPP_INCLUDED

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